The invention relates to a continuously operating strip-casting and rolling system with strip tension control, including a casting unit with a melt-containing feed vessel with a horizontally disposed casting trough and a discharge area configured as a casting nozzle and two guide pulleys and a primary cooling zone having a revolving chilled casting strip, and at least one downstream rolling unit composed of at least two drivable rollers.
A continuous strip-casting and rolling system is known, for example, from steel research 74 (2003), No. 11/12, page 724-731. In particular, this production process which is known as DSC method (Direct Strip Casting) is suitable for the production of a hot strip from lightweight steel having a high manganese content.
In this known process, the melt is loaded from a feed vessel via a casting channel and a discharge area of a casting machine constructed as a casting nozzle in form of a siphon onto a revolving casting belt of a horizontal strip-casting system. As a result of intensive cooling of the casting strip, the supplied melt solidifies to form a pre-strip with a thickness ranging from 6-20 mm. After solidification throughout, the pre-strip is subjected to a hot rolling process.
Casting, rolling and coiling the steel strip requires from strip caster that the cast strand is removed from the casting machine with very little pulling force, ideally with zero pulling force. In particular, the known lightweight steels with a high manganese content have a tendency for strip breakage already at low strip pulling forces, especially when the strip is not yet fully solidified throughout, resulting in system downtime and increased repair costs.
In general, strip tension controls for continuously operating rolling mills are known, for example from DE 101 37 246 A1 or DE 26 18 901 C2. However, these devices designed for strip tension control in continuously operating rolling mills are not sufficient to control and maintain the strip tension between the casting unit and the downstream rolling unit at a sufficiently low level that band breakage can be reliably prevented.